About integrated circuits (ICs), large scale integrated circuits (LSIs), and light emitting diodes (LEDs) and other electronic components (that is, electronic components each having at least one semiconductor element), electrical properties thereof are examined by bringing an electrical contact member (contact probe) used in a connecting device for examination into contact with an electrode of the semiconductor element. The electrical contact member is required to have not only a good electroconductivity (a low contact resistance value) but also such an excellent endurance that the member is not worn away or damaged even when repeatedly brought into contact with the electrode, which is a test subject.
The contact resistance value of the electrical contact member is generally set to 100 mΩ or less. However, when a test subject is repeatedly examined therewith, the contact resistance value may be deteriorated into a value from several hundred milliohms to several ohms. Conventionally, therefore, the electrical contact member is periodically cleaned or exchanged with another member. However, such an operation remarkably decreases the reliability of the examining step or the operating rate of the connecting device for examination. Thus, development has been advanced about electrical contact members that are not lowered in contact resistance value even when repeatedly used over a long term. In particular, when an electrode that is a test subject is soldered, plated with tin (Sn) or subjected to some other treatment, the surface of the electrode is shaved away by contacting thereof with an electrical contact member since the solder or tin is soft. Thus, the electrical contact member has a property that wastes, shavings, or the like therefrom adheres easily to the tip portion of the electrical contact member. Furthermore, the adhering solder or tin is being oxidized so that the contact resistance value is not easily kept at a stable level.
For example, Patent Literatures 1 to 3 disclose a method for stabilizing the contact resistance value of an electrical contact member. Of these literatures, Patent Literature 1 discloses an amorphous hard coat made mainly of carbon, or carbon and hydrogen; to this coat, an impurity element other than carbon and hydrogen being added in the range of 0.001 to 40% by atom, and this element being selected from the group consisting of V, Cr, Zr, Nb, Hf, Ta, Au, Pt and Ag; thereby having an excellent abrasion resistance and a high electroconductivity, being small in film stress, and having a good sliding property. The literature states that this hard coat is favorably applicable to a sliding region for which electrical contacting is required.
Patent Literature 2 discloses a probe made of tungsten or rhenium tungsten, wherein a DLC film is formed onto at least a tip portion of a contact region of the probe at the tip of the probe, and the DLC film contains, in a proportion of 1 to 50% by mass, at least one metal of tungsten, molybdenum, gold, silver, nickel, cobalt, chromium, palladium, rhodium, iron, indium, tin, lead, aluminum, tantalum, titanium, copper, manganese, platinum, bismuth, zinc, and cadmium. The literature states that the probe having this structure does not easily undergo adhesion of aluminum wastes even when repeatedly brought into contact with an aluminum electrode, and makes it possible to stabilize the contact resistance into a low value even when not frequently cleaned.
Patent Literature 3 discloses an electrical-property-measuring probe about which at least a surface of a probe material thereof to which ions are to be implanted is made mainly of any one, or two or more of beryllium-copper alloy, copper, silver, gold, nickel, palladium, platinum, rhodium, rhenium, chromium, molybdenum and tungsten. Patent Literature 3 states that in order to cause the probe to exhibit an alien-substance-adhering effect onto the topmost surface of the probe, the average carbon concentration in a shallow region of the probe from the topmost surface to a depth of 50 nm is controlled into about 1 to 80% by atom, whereby the probe does not easily undergo adhesion of any alien substance even when repeatedly brought into contact with an element-side-electrode (made of solder, or the like) so that the frequency of cleaning can be decreased.